1971 340 Build - Choosing piston rings dilemma

70Hardtop said
Good idea if he was into performance engines and had that type of knowledge but he's 74 years old and runs just a regular machine shop. One day he's be doing machine work on a Toyota 4 cyl engine, next will be rods from a Top Fuel drag car, next day will be will be a rebore on a lawnmower engine.

He doesn't have much interest in the parts. He would just say throw in some no-name cast rings.

Right on. Kinda how most shops run, whatever you take in that's brought to you

I worked at a machine shop long ago...and as I was being run through the operating of the sunnen hone..i remember Toyota came up in regards to which stones to use and hardness of diff blocks..so on that block you would use a fine stone because they have pretty hard castings...and on a a 350 etc a course stone in comparison. So he would know what grit and then and wether he used a plateau brush etc. Therebis more to that story, of course...but more than likely he could use a basic moly ring, or cast and maybe notice a duration diff in break in with regular cast seating almost instantly as where the moly might take longer. Too rough and it will take many mile to seat a moly ring in my experience. I did it with a 225... must have what seemed like 10k.
I got 160k or so out of it before I sold it. It had a ridge at about 70k when I changed the head for a big valve upgrade.